The San Jose Police Department’s home page also suffered from a lengthy outage during what is called a "denial of service attack," overwhelming the website from the outside so residents could not use it.

But hackers could potentially get access to what is inside the website.

"When it comes to cities there's a lot of information, said Steve Pao of Barracuda Networks, a Campbell-based company specializing in security and data protection solutions. "Parks and rec departments have information not only on citizens, but citizen's children."